Fluoroelastomer, curable composition and cured rubber article

Abstract

A noncrystalline fluoroelastomer which is a copolymer consisting essentially of vinylidene fluoride and a fluoromonomer represented by the general formula (1): CH2=CFRf(1) wherein Rf is a straight or branched fluoroalkyl group containing 1 to 12 carbon atoms, and has a vinylidene fluoride units/fluoromonomer units mol ratio of 78/22 to 22/78 and a glass transition temperature of not higher than 25° C.

The invention claimed is: 
     
       1. A noncrystalline fluoroelastomer which is a copolymer comprising vinylidene fluoride, a fluoromonomer represented by the general formula (1):
   CH 2 ═CFR f   (1)
 
 wherein R f  is a straight or branched fluoroalkyl group containing 1 to 12 carbon atoms, and another monomer copolymerizable with both vinylidene fluoride and said fluoromonomer of formula (1), and
 has a vinylidene fluoride units/fluoromonomer units mol ratio of 85/15 to 20/80, contains the other monomer units in the amount of 0 to 50 mol percent of all the monomer units, 
 has a glass transition temperature of not higher than 25° C. and 
 contains at least one iodine atom and/or at least one bromine atom, the total content thereof being 0.001 to 10% by weight. 
 
 
     
     
       2. The fluoroelastomer according to  claim 1 ,
 which is a copolymer consisting essentially of vinylidene fluoride and a fluoromonomer represented by the general formula (1):
   CH 2 ═CFR f   (1)
 
 
 
       wherein R f  is a straight or branched fluoroalkyl group containing 1 to 12 carbon atoms, and has a vinylidene fluoride units/fluoromonomer units mol=ratio of 80/20 to 20/80. 
     
     
       3. The fluoroelastomer according to  claim 1 ,
 wherein the vinylidene fluoride units/fluoromonomer units mol ratio is 85/15 to 50/50 and the other monomer units amount to 1 to 50 mol percent of all the monomer units. 
 
     
     
       4. The fluoroelastomer according to  claim 1 ,
 wherein the fluoromonomer is 2,3,3,3-tetrafluoropropene. 
 
     
     
       5. A curable composition comprising the fluoroelastomer according to  claim 1 , and a curing agent. 
     
     
       6. The curable composition according to  claim 5 ,
 which contains an organic peroxide as the curing agent. 
 
     
     
       7. A cured rubber article obtained by curing the curable composition according to  claim 5 .